Prominent laterality of the posterior cerebral artery at three-dimensional time-of-flight MR angiography in M1-segment middle cerebral artery occlusion

BACKGROUND AND PURPOSE: Three-dimensional time-of-flight MR angiography (3D TOF MRA) often discloses prominent posterior cerebral artery (PCA) laterality in the setting of M1-segment middle cerebral artery (MCA) occlusion. We sought to analyze the implications of prominent PCA laterality at 3D TOF MRA. METHODS: We retrospectively reviewed 3D TOF MRA and digital subtraction angiography (DSA) findings in 25 patients (12 male, 13 female; mean age, 68.8 years [age range, 29-94 years]) with M1-segment occlusion. The observable laterality of the PCA, determined on the basis of 3D TOF MRA findings, was scored according to distal signal extent and compared with findings of collateral flow from the ipsilateral PCA via the leptomeningeal anastomosis (LMA) at DSA. Frequency of PCA laterality at 3D TOF MRA in patients and that in 56 healthy control subjects was also compared. RESULTS: The positive predictive value of PCA laterality for the existence of collateral flow was 99.9% and the negative predictive value 30.7%. The distal extent of ipsilateral PCA signal at 3D TOF MRA positively correlated with the grade of collateral flow from the PCA via the LMA (r = 0.802; P <.01). PCA laterality was significantly less common in control subjects (P <.01). CONCLUSION: Prominent PCA laterality at 3D TOF MRA in patients with M1-segment occlusion represents the existence of collateral flow from the PCA via the LMA.     

急性脑梗死合并脑白质疏松的危险因素分析

 目的 探讨急性脑梗死合并脑白质疏松(leukoaraiosis,LA)发生的危险因素。方法 选取急性脑梗死患者207例,按是否合并LA分为合并LA组93例,未合并LA组114例,收集两组患者年龄、高血压、脑梗死史、HCY、hsCRP、性别、吸烟史、饮酒史、糖尿病、高脂血症、冠心病等临床资料,分别采用单因素分析及多因素Logistic回归分析对以上可能的危险因素进行分析。结果 (1)单因素分析:LA组与无LA组比较,年龄、高血压、脑梗死史、HCY、hsCRP差异有统计学意义(P＜0.05),性别、吸烟史、饮酒史、糖尿病、高脂血症、冠心病比较无统计学差异。(2)多因素Logistic回归分析:年龄、高血压、脑梗死病史、HCY、hsCRP为LA发生的危险因素(P<0.05)。结论 年龄、高血压、脑梗死病史、HCY、hsCRP与LA发生有关;性别、吸烟史、饮酒史、糖尿病、高脂血症、冠心病与LA发生无关。     

无肝硬化乙肝患者肝癌发病影响因素分析

 目的 探讨无肝硬化乙肝相关肝癌患者的发病因素。方法 收集2004-01至2015-12月我院就诊的原发性肝癌共1000例。根据是否有肝硬化分为肝硬化组(n=934例)及无肝硬化组(n=66例),回顾性分析2组患者的一般情况及实验室检查指标等资料,对无肝硬化乙肝相关肝癌患者的发病因素进行χ²检验及Logistic回归分析。结果 单因素分析表明2组患者在年龄、是否饮酒、是否重叠丙型肝炎病毒感染、是否合并高血压、基线血清e抗原状态及血清HBV DNA水平、是否行抗病毒治疗与是否有肝癌家族史方面差异有统计学意义(P<0.05);将其纳入多因素非条件Logistic回归分析,结果提示饮酒(OR=0.176,P=0.002)、有高血压病史(OR=0.505,P=0.039)、基线血清HBV DNA水平偏低(OR=0.031,P＜0.001)、既往未行抗病毒治疗(OR=7.268,P＜0.001)、有肝癌家族史(OR=0.487,P=0.010)是无肝硬化慢性乙型肝炎患者直接进展为原发性肝癌的独立危险因素。结论 对于有饮酒史、有高血压病史、基线血清HBV DNA水平偏低、既往未行抗病毒治疗及有肝癌家族史的无肝硬化慢性乙型肝炎患者,应密切监测肝癌的发生。     

Bolus arterial-venous transit in the lower extremity and venous contamination in bolus chase three-dimensional magnetic resonance angiography

RATIONALE AND OBJECTIVES: To investigate the phenomena and causes for undesired venous signal in the distal station of bolus chase 3D MRA. METHODS: Consecutive patients (in 8 months) undergoing peripheral MRA consisting of 2D projection MRA of the tibial trifurcation and 3D bolus chase MRA were retrospectively evaluated. Venous contamination in mid-calf in bolus chase 3D MRA was correlated to the arterial phase duration, the time between the contrast bolus arrival and venous return measured on time resolved 2D images. Statistical analyses were performed to identify the clinical parameters indicative of venous contamination. RESULTS: The arterial phase durations at the mid-calf were 49 +/- 8 seconds on 101 legs without venous signal in the bolus chase 3D MRA, 35 +/- 9 seconds on 13 legs with moderate venous signal, and 20 +/- 4 seconds on 40 legs with substantial venous signal; the differences were significant among different venous signal levels (P < 0.001 for all pairs). Legs with cellulitis had shorter arterial phase and more venous contamination than legs without cellulitis (P < 0.05). Patients with myocardial infarction had longer arterial phase and less venous contamination than patients without myocardial infarction (P < 0.01). CONCLUSION: Venous signal in the distal calf station of bolus chase 3D peripheral MRA is caused by fast arterial-venous transit. It is worse in legs with cellulitis and less in patients with a history of myocardial infarction.     

原发性痛风危险因素的研究

 目的 探讨原发性痛风的危险因素。方法 病例-对照研究1996年1月～2000年1月专科门诊132名新患者,资料处理采用条件Logistic回归分析。结果 原发痛风的独立危险因素：职业、外向性格、饮酒、高嘌呤膳食、高血压及家族史、冠心病及家族史、目前收缩压和舒张压、体质指数(BMI)、尿酸清除分数、急性痛风关节炎发作部位的外伤史、痛风家族史、甘油脂(TG)、总胆固醇(TC)、低密度脂蛋白胆固醇(LDL)、极低密度脂蛋白胆固醇(VLDL)的升高及高密度脂蛋白胆固醇2(HDL2C)的降低。结论 国人对于原发痛风的危险因素应早期预防。     

Saturation recovery-prepared magnetic resonance angiography for assessment of left atrial and esophageal anatomy

Objectives:Magnetic resonance angiography (MRA) has been established as an important imaging method in cardiac ablation procedures. In pulmonary vein (PV) isolation procedures, MRA has the potential to minimize the risk of severe complications, such as atrio-esophageal fistula, by providing detailed information on esophageal position relatively to cardiac structures. However, traditional non-gated, first-pass (FP) MRA approaches have several limitations, such as long breath-holds, non-uniform signal intensity throughout the left atrium (LA), and poor esophageal visualization. The aim of this observational study was to validate a respiratory-navigated, ECG-gated (EC), saturation recovery-prepared MRA technique for simultaneous imaging of LA, LA appendage, PVs, esophagus, and adjacent anatomical structures.Methods:Before PVI, 106 consecutive patients with a history of AF underwent either conventional FP-MRA (n = 53 patients) or our new EC-MRA (n = 53 patients). Five quality scores (QS) of LA and esophagus visibility were assessed by two experienced readers. The non-parametric Mann–Whitney U-test was used to compare QS between FP-MRA and EC-MRA groups, and linear regression was applied to assess clinical contributors to image quality.Results:EC-MRA demonstrated significantly better image quality than FP-MRA in every quality category. Esophageal visibility using the new MRA technique was markedly better than with the conventional FP-MRA technique (median 3.5 [IQR 1] vs median 1.0, p < 0.001). In contrast to FP-MRA, overall image quality of EC-MRA was not influenced by heart rate.Conclusion:Our ECG-gated, respiratory-navigated, saturation recovery-prepared MRA technique provides significantly better image quality and esophageal visibility than the established non-gated, breath-holding FP-MRA. Image quality of EC-MRA technique has the additional advantage of being unaffected by heart rate.Advances in knowledge:Detailed information of cardiac anatomy has the potential to minimize the risk of severe complications and improve success rates in invasive electrophysiological studies. Our novel ECG-gated, respiratory-navigated, saturation recovery-prepared MRA technique provides significantly better image quality of LA and esophageal structures than the traditional first-pass algorithm. This new MRA technique is robust to arrhythmia (tachycardic, irregular heart rates) frequently observed in AF patients.     

原发痛风的临床特点及高危因素分析

 目的对原发痛风的临床特点及高危因素进行分析.方法病例选自2002年1月～2004年12月在痛风门诊就诊的165例新患者,资料处理采用条件Logistic回归分析.结果发病年龄范围24～72岁,男163例,女2例.首发部位以第1跖趾关节最常见138例(86.3%).原发痛风的独立危险因素:高血压及家族史、冠心病及家族史、目前收缩压和舒张压、BMI、尿酸排泄分数、急性痛风关节炎发作部位的外伤史、痛风家族史、TG、TC、LDL、VLDL的升高及HDL2-C的降低.结论国人对于原发痛风的危险因素应早期预防.     

Retrospective assessment of risk factors to predict tunneled hemodialysis catheter outcome

PURPOSE: To identify factors that may influence the function, outcome, and complications associated with tunneled hemodialysis catheters. MATERIALS AND METHODS: Radiology reports and hemodialysis, medical, and Clinical Information System (computerized patient medical record system) records were retrospectively reviewed in 221 consecutive patients who underwent tunneled hemodialysis catheter placement by interventional radiologists between January 11, 1996 and January 13, 2000 at Dartmouth-Hitchcock Medical Center. Various patient characteristics (diabetes, smoking, hypertension, age, sex, atherosclerotic cardiovascular disease, history of cardiac catheterization, coumadin use, functional status, and obesity) were assessed for their relationship to the outcome of hemodialysis catheters. Catheter outcome was examined by calculating infection rate, thrombosis rate, fibrin formation rate, mechanical malfunction rate, and total complication rate. With these patient characteristics and outcome variables, multiple regression analysis was performed with STATA (College Station, TX) statistical analysis software. RESULTS: Of the 221 patients reviewed, 39 patients were lost to follow-up. Among the remaining 182 patients, 427 catheters were placed for a total number of 36994 catheter-days. For overall complication rate, multiple regression analysis revealed a statistically significant positive correlation only for hypertension (P =.032). Total complication rate was 0.76 events per 100 catheter-days (95% CI: 0.53-1.00) for patients with a documented history of hypertension and 0.27 events per 100 catheter-days (95% CI: 0.08-0.45) for patients without (P =.024, paired student t test). For patients with diabetes versus patients without, the infection rates were 0.34 episodes per 100 catheter-days (95% CI: 0.15-0.53) and 0.12 episodes per 100 catheter-days (95% CI: 0.06-0.18), respectively, (P =.011, paired student t test). Thrombosis rate for patients on coumadin was 0.13 events per 100 catheter-days (95% CI: -0.14-0.40), while thrombosis rate for patients not taking coumadin was 0.03 events per 100 catheter-days (95% CI: 0-0.05) (P =.036, paired student t test). CONCLUSION: Hypertension is a risk factor for poor outcome of tunneled hemodialysis catheters as measured by total complication rate requiring catheter removal or exchange. In this retrospective study, no other specific risk factors predicted an increased need for removal or exchange of tunneled hemodialysis catheters.     

Arterial spin-labeling MR imaging in moyamoya disease compared with clinical assessments and other MR imaging finings

Purpose

Our purpose was to identify the causal factors for the perfusion distribution obtained with ASL-MRI by comparing ASL-MRI with clinical information and other MRI findings in moyamoya disease.

Methods

Seventy-one patients with moyamoya disease underwent ASL-MRI and other MRI, including fluid-attenuated inversion recovery imaging (FLAIR) and three-dimensional time-of-flight magnetic resonance angiography (MRA) on 3.0-Tesla MRI system. Cerebral blood flow (CBF) values (ASL values) for the cerebral hemispheres (142 sides) were measured on CBF maps generated by ASL-MRI. Relationships between the ASL values and the following 9 factors were assessed: sex, family history, revascularization surgery, age at MR exam, age at onset, the steno-occlusive severity on MRA (MRA score), degree of basal collaterals, degree of leptomeningeal high signal intensity seen on FLAIR, and size of ischemic or hemorrhagic cerebrovascular accident lesion (CVA score).

Results

Patients with a family history had significantly higher ASL values than those without such a history. There were significant negative correlations between ASL values and age at MR exam, MRA score, and CVA score.

Conclusions

ASL-MRI may have cause-and-effect or mutual associations with family history, current patient age, size of CVA lesion, and intracranial arterial steno-occlusive severity in Moyamoya disease.     

Carotid artery calcification seen on panoramic dental radiographs in the Asian population in Japan

OBJECTIVES: To determine the frequency of carotid artery calcification (CAC) seen on panoramic dental radiographs, the relationship between the condition and a history of cerebral infarction (CI), and the history of the risk factors of CI in patients in Japan. METHODS: A total of 2374 individuals whose panoramic radiographs were obtained at their first consultation were reviewed. Result: CAC was found in 95 subjects (4.0%) and was found at a higher frequency in patients with a history of CI than in those without a history of CI. The modifiable risk factors (a history of hypertension, diabetes and hypercholesterolaemia) and CAC showed significant relationship in the chi(2) test for pairwise comparison. When age and gender were added and all of these risk factors were considered simultaneously in the multiple logistic regression analysis, age and history of hypercholesterolaemia remained statistically significant. CONCLUSIONS: CAC may be seen on panoramic dental radiographs and is related to the patients' general history of CI, and the risk factors of CI in the Asian population in Japan.     

Time-resolved MR angiography: optimal parallel imaging method

BACKGROUND AND PURPOSE: Time-resolved (TR) MR angiography (MRA) using parallel imaging techniques is proving to have clinical utility for improving MRA spatial and temporal resolution and separating arterial from venous anatomy. The purpose of this study was to evaluate TR MRA of the intracranial vessels at different integrated parallel acquisition technique (IPAT) factors. MATERIALS AND METHODS: 3D TR MRA using time-resolved echo-shared angiographic technique was performed with different IPAT factors (0, 2, 3) at 1.5 T, resulting in temporal resolutions of 4.0, 1.7, and 1.3 seconds, respectively. We studied 14 subjects, comprising 12 patients with various pathologic conditions and 2 healthy subjects. The brain volume was covered by 36 partitions, and a bolus of 5 mL of gadopentate dimeglumine was administered. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), the number of frames that distinguished between arterial and venous phases, the conspicuity of the vasculature, and artifacts were analyzed. RESULTS: There was no significant difference in SNR between IPAT factors 0 and 2. Moreover, SNR was significantly lower with IPAT 3 than with IPAT 0 or 2. Smaller vessel segments (M3 and P3) were rated significantly inferior with TR MRA IPAT 2 or 3 compared with MRA without IPAT. For larger proximal vessels (A1 and A2 segments of anterior cerebral artery, M1 and M2 segments of middle cerebral artery, P2 segment of posterior cerebral artery, and basilar artery), there was no difference between TR MRA IPAT 0 and 2. CONCLUSION: To obtain arterial and venous information in a clinical setting, intracranial TR MRA is best performed with an IPAT factor of 2 with at least 5 mL of contrast.     

Postoperative assessment of extracranial-intracranial bypass by time-resolved 3D contrast-enhanced MR angiography using parallel imaging

PURPOSE: Our goals were to assess image quality of time-resolved contrast-enhanced MR angiography (CE MRA), by using 3D data acquisition along with a parallel imaging technique that can improve temporal resolution and to compare this technique with 3D-time-of-flight (TOF) MRA in the postoperative assessment of extracranial (EC)-intracranial (IC) bypass surgery. METHODS: On a 1.5T imaging system, we performed CE MRA by using a 3D fast field-echo sequence in combination with a parallel imaging technique, to obtain images in the coronal plane centered at the postoperative site. Our patient group comprised 17 patients, including 13 after superficial temporal artery-middle cerebral artery (MCA) anastomosis, 3 after external carotid artery-MCA anastomosis, and one after extracranial vertebral artery-posterior cerebral artery anastomosis. Visualization of the anastomosis and the distal flow on the CE-MRA images was assessed comparatively with that on 3D-TOF MR angiograms obtained at the same time. In 6 patients, we also compared the efficiency of visualization on CE-MRA images with that on conventional angiograms. RESULTS: A temporal resolution of 0.8 s/frame could be achieved with the technique employed. The bypass was better demonstrated postoperatively on CE-MRA images than on 3D-TOF MR angiograms in 13 patients (76%), whereas the 2 methods were equivalent in 4 patients (24%). Good correspondence of results was observed in the 6 patients for whom CE MRA and conventional digital subtraction angiography (DSA) images were compared. CONCLUSION: CE MRA by using the parallel imaging technique can increase image acquisition speed with sufficient image quality. This technique is at least equivalent to 3D-TOF MRA to evaluate the postoperative status of EC-IC bypass.     

Accuracy of pre- and postcontrast 3D time-of-flight MR angiography in patients with acute ischemic stroke: correlation with catheter angiography

BACKGROUND AND PURPOSE: 3D time-of-flight (TOF) MR angiography (MRA) is insensitive to slow flow; however, the use of MR imaging contrast agents helps to visualize slow-flow vessels and avoids overestimation of vascular occlusion. The purpose of this study was to correlate pre- and postcontrast 3D TOF MRA with the results of conventional angiography during endovascular reperfusion therapy and to determine the accuracy of postcontrast 3D TOF MRA. MATERIALS AND METHODS: Thirteen patients who underwent endovascular reperfusion therapy for acute ischemic stroke were retrospectively analyzed. MR imaging techniques included single-slab 3D TOF MRA with and without contrast, as well as perfusion-weighted imaging. Angiography during reperfusion therapy was used as a standard of reference. Affected arteries were divided into segments either proximal or distal to the lesion, and pre- and postcontrast MRA signals were graded as absent, diminished or narrowed, or normal. RESULTS: In 2 of 5 patients with arterial stenosis and 6 of 8 patients with complete occlusion, MRA signal intensity proximal to each lesion was absent, indicating a proximal pseudo-occlusion on precontrast MRA. Postcontrast MRA demonstrated an arterial signal intensity proximal to the stenotic or occlusive lesions in all 13 patients. Arterial signal intensity distal to the occlusion was identified on postcontrast MRA in 7 of 8 patients having complete occlusion, and the extent of occlusion on postcontrast MRA was similar to results of conventional angiography. CONCLUSION: In this small series, postcontrast 3D TOF MRA more accurately delineated the extent of stenotic or occlusive arterial lesions than precontrast MRA.     

MR angiography in internal carotid artery dissection: improvement of diagnosis by selective demonstration of the intramural haematoma

We studied eight consecutive patients with clinical and intra-arterial angiographic (DSA) diagnosis of internal carotid artery (ICA) dissection to analyse the accuracy of MRA in dissections, using a new technique with presaturation pulses. Spin-echo images of the head were followed by three-dimensional time-of-flight (TOF) MRA at the site of the dissection, with and without a special caudal saturation pulse in addition to the cranial one. The accuracy of MRA was assessed in 64 segments of 16 ICA, all examined with DSA and MRA. High-signal intramural haematoma in the ICA at the level of the dissection was observed in all patients either on the maximal-intensity projection (MIP) reconstructions or on the partitions with this presaturation pulse technique. MRA had a sensitivity to detect dissected vessels of 100 %. Specificity for vessels correctly identified as not having a lesion was also 100 %. There was good correlation between DSA and MRA in demonstrating the site of the dissected ICA segment and the degree of stenosis. In only two cases was there overestimation of the degree of stenosis on the MIP reconstructions of the 3-D MRA. Received: 5 January 1998 Accepted: 30 April 1998     

舟山市高血压现况调查及危险因素分析

目的探讨海岛地区高血压的发病特点及危险因素，为海岛地区高血压社区综合防治措施的制定和开展提供依据。方法对海岛的城市、农村地区15岁以上1174人进行高血压患病和危险因素调查。结果（1）高血压总患病率31．69％，标化率14．96％。性别与地区间均无明显差异。（2）高血压患病随年龄递增，40岁始患病率明显增高。（3）高血压危险因素为超重、高血糖、高血脂、高龄、高血压家族史及饮酒；血压与性别、吸烟、食盐摄人量无相关性。结论（1）海岛高血压患病率呈快速上升趋势；（2）患病年龄有提前趋势；（3）超重、高血糖、高血脂是目前海岛高血压的最主要危险因素。     

Catheter angiography, MR angiography, and MR perfusion in posterior reversible encephalopathy syndrome

BACKGROUND AND PURPOSE:The cause of posterior reversible encephalopathy syndrome (PRES) is unknown. Two primary hypotheses exist: 1) hypertension exceeding auto-regulatory limits leading to forced hyper-perfusion and 2) vasoconstriction and hypo-perfusion leading to ischemia with resultant edema. The purpose of this study was to evaluate the catheter angiography (CA), MR angiography (MRA), and MR perfusion (MRP) features in PRES in order to render further insight into its mechanism of origin.MATERIALS AND METHODS:In 47 patients with PRES, 9 CAs and 43 MRAs were evaluated for evidence of vasculopathy (vasoconstriction and vasodilation), and 15 MRP studies were evaluated for altered relative cerebral blood volume (rCBV) in PRES lesions and regions. Visualization of vessels on MRA and toxicity blood pressures were compared with the extent of hemispheric vasogenic edema.RESULTS:Vasculopathy was present in 8 of 9 patients on CA (direct correlation to MRA in 3/6 patients). At MRA, moderate to severe vessel irregularity consistent with vasoconstriction and vasodilation was present in 30 of 43 patients and vessel pruning or irregularity in 7 patients, with follow-up MRA demonstrating reversal of vasoconstriction or vasodilation in 9 of 11 patients. Vasogenic edema was less in patients with hypertension compared with patients who were normotensive. Preserved normal length of the posterior cerebral artery (PCA) was commonly seen in patients with severe hypertension despite diffuse or focal vasoconstriction or vasodilation. In these patients, lengthier visualization of the distal PCA correlated with a lower grade of hemispheric edema (P = .002). Cortical rCBV was significantly reduced in 51 of 59 PRES lesions and regions compared with a healthy reference cortex (average 61% of reference cortex) with mild decrease in the remainder.CONCLUSION:Vasculopathy was a common finding on CA and MRA in our patients with PRES, and MRP demonstrated reduced cortical rCBV in PRES lesions. Vasogenic edema was reduced in patients with hypertension, and superior distal PCA visualization correlated with reduced hemispheric edema in patients with PRES and severe hypertension.

Neurotoxicity with development of posterior reversible encephalopathy syndrome (PRES) is commonly seen in association with cyclosporine and FK-506 immune suppression after transplantation (allogeneic bone marrow transplantation [allo-BMT], solid organ transplantation); preeclampsia and eclampsia; infection, sepsis, and shock; nonspecific medical renal disease; and in autoimmune conditions as well as after high-dose chemotherapy.^1-13 The mechanism behind the development of PRES is yet unproved. Two broad theories have generally been considered.Severe hypertension with autoregulatory failure and hyperperfusion is often cited as the underlying mechanism. Alternatively, vasospasm has been demonstrated (catheter angiography [CA], MR angiography [MRA]), decreased cerebral blood flow noted (MR perfusion [MRP], single-photon emission CT [SPECT]) and the imaging appearance typically resembles a watershed distribution suggesting a mechanism related to brain hypoperfusion.^{1-3,5,9,13-20}Given these opposing views, it was our opinion that parallel observations on CA, MRA, and MRP could render further insight into the state of brain perfusion in PRES. Therefore, the purpose of this study was to retrospectively evaluate the CA, MRA, and MRP features in a large group of patients with PRES.     

Noncontrast 3D steady state free precession magnetic resonance angiography of the thoracic central veins using nonselective radiofrequency excitation over a large field of view: initial experience

PURPOSE: To evaluate the feasibility of three-dimensional (3D) steady state free precession (SSFP) magnetic resonance angiography (MRA) using nonselective radiofrequency excitation for the assessment of thoracic central veins. MATERIALS AND METHODS: Thirty consecutive patients (17 males, 13 females, age range 22-76) with various cardiac and thoracic vascular diseases underwent free-breathing electrocardiogram-gated noncontrast SSFP MRA and conventional high-resolution 3D contrast-enhanced (CE) MRA of the thorax at 1.5 T. Two readers evaluated both datasets for findings: venous visibility and sharpness (from 0, not visualized to 3, excellent definition); artifacts; signal-to-noise ratio (SNR); and contrast-to-noise ratio (CNR) in 8 venous segments including superior vena cava (SVC), supra-diaphragmatic inferior vena cava, bilateral brachiocephalic, proximal subclavian, and lower internal jugular veins. Statistical analysis was performed using Wilcoxon test for overall image quality and vessel visibility, t test for SNR and CNR analysis, and kappa coefficient for inter-observer variability. RESULTS: 3D SSFP and CE-MRA were successfully performed in all patients. Scan time for SSFP MRA ranged from 5 to 10 minutes (mean +/- standard deviation, 7 +/- 2 minutes). Reader 1 (2) graded the overall image quality as excellent and good on SSFP MRA in 23 (25) and 7 (5) patients, and on CE-MRA in 22 (23) and 8 (9) patients, respectively. On SSFP MRA, readers 1 and 2 graded 234 (97.5%) and 233 (97.1%) venous segments with diagnostic definition (grades 2 and 3) (kappa = 0.69), respectively. On conventional CE-MRA, readers 1 and 2 graded 231 (96.3%) and 232 (96.7%) venous segments with diagnostic definition (grades 2 and 3) (kappa = 0.68), respectively. Segmental visibility and sharpness were higher for lower internal jugular veins on CE-MRA for each reader (P < 0.001). No significant difference existed for venous visibility and sharpness scores for other venous segments between the 2 techniques for both readers (P > 0.05). SNR and CNR values were lower for internal jugular veins on SSFP MRA (P < 0.001). No significant difference existed between SNR and CNR values for the other venous segments on SSFP and CE-MRA (P > 0.05 for all). The 2 readers demonstrated patent SVC Glenn shunt to main pulmonary artery (n = 3), patent extra cardiac Fontan shunt from inferior vena cava to pulmonary artery confluence (n = 2), and dilatation and thrombosis of SVC (n = 1) and right brachiocephalic vein (n = 1) on both datasets. CONCLUSION: Free breathing navigator-gated noncontrast 3D SSFP MRA with nonselective radiofrequency excitation provides high image quality and sufficient SNR and CNR for confident evaluation of thoracic central veins.     

Prevalence of Unruptured Intracranial Aneurysm on MR Angiography

Objective

To evaluate the prevalence of incidentally found unruptured intracranial aneurysms (UIAs) on the brain MR angiography (MRA) from a community-based general hospital.

Materials and Methods

This was a prospectively collected retrospective study, carried out from January 2004 to December 2004. The subjects included 3049 persons from a community-based hospital in whom MRA was performed according to a standardized protocol in an outpatient setting. Age- and sex-specific prevalence of UIAs was calculated. The results by MRA were compared with intra-arterial digital subtraction angiography (DSA) findings.

Results

Unruptured intracranial aneurysms were found in 137 (5%) of the 3049 patients (M:F = 43:94; mean age, 60.2 years). The prevalence of UIAs was 5% (n = 94) in women and 4% (n = 43) in men, respectively (p = 0.2046) and showed no age-related increase. The most common site of aneurysm was at the distal internal carotid artery (n = 64, 39%), followed by the middle cerebral artery (n = 40, 24%). In total, 99% of aneurysms measured less than 12 mm, and 93% of aneurysms measured less than 7 mm. Direct comparisons between MRA and DSA were available in 70 patients with 83 UIAs; the results revealed two false positive and two false negative results.

Conclusion

This community-hospital based study suggested a higher prevalence of UIAs observed by MRA than previously reported. These findings should be anticipated in the design and use of neuroimaging in clinical practice.     

Hybrid of opposite‐contrast MRA of the brain by combining time‐of‐flight and black‐blood sequences: Initial experience in major trunk stenoocclusive diseases

Purpose:

To assess the feasibility of a new MR angiography (MRA) technique named hybrid of opposite‐contrast MRA (HOP MRA) that combined the time‐of‐flight (TOF) MRA with a flow‐sensitive black‐blood (FSBB) sequence in the diagnosis of major trunk stenoocclusive diseases.

Materials and Methods:

On a 1.5 Tesla imager using a dual‐echo three‐dimensional (3D)‐gradient‐echo sequence, we obtained the first echo for TOF MRA followed by the second echo for FSBB. We then subtracted the FSBB data set from that of TOF MRA followed by maximum intensity projection. In four normal volunteers and 19 patients with chronic stenoocclusive disease of the major trunk, we performed HOP MRA along with 3D‐TOF MRA and compared the findings.

Results:

In the volunteer group, the HOP MRA technique improved the demonstration of distal arterial branches. In 12 of the 19 patients, the HOP MRA better visualized branches distal to the lesion as well as distal branches of normal trunks than 3D‐TOF MRA, while both techniques provided equivalent depiction of branches distal to the lesion but better depiction of normal distal branches in three patients.

Conclusion:

The HOP‐MRA technique is promising in major trunk stenoocclusive diseases as it better demonstrates distal branches probably representing collaterals than 3D‐TOF MRA. J. Magn. Reson. Imaging 2010;31:56–60. © 2009 Wiley‐Liss, Inc.     

脑肿瘤磁共振血管成像的初步研究

目的：应用ＴＯＦ法ＭＲＡ显示脑肿瘤的肿瘤血管、供血动脉、引流静脉和脑血管移位与侵犯等，以探讨ＭＲＡ无创性评价脑肿瘤的价值。材料与方法：对４３例脑肿瘤患者进行了ＴＯＦ法ＭＲＡ（ｎ＝４３）与脑血管造影（ｎ＝１５）和／或手术结果（ｍ＝４１）对比评价。采用１．０Ｔ超导ＭＲ系统，二维或三维ＦＩＳＰ扫描，用或不用预饱和技术和Ｇｄ－ＤＴＰＡ，ＭＩＰ重建获取ＭＲＡ图像。结果：ＭＲＡ准确了７６．２％的肿瘤富血管度，